PBL 3796, PBL 3796/2
PBL 3796 is an analog Subscriber Line Interface Circuits (SLICs), which are fabrica-
ted in a 75 V bipolar, monolithic process.
The programmable battery feed is resistive with short-loop current limiting. A
switch-mode regulator reduces on-chip power dissipation in the active state. In the
standby state, power dissipation is further reduced, while still permitting supervisory
functions to be active.
Tip-ring polarity is reversible without altering SLIC supervisory and voice frequency
(vf) functions. Tip and ring outputs can be set to high impedance states. These and
other operating states are activated via a parallel, four bit control word.
An external resistor controls the off-hook detector threshold current. The ring trip
detector can operate with both balanced and unbalanced ringing systems. The two
detectors are read via a shared output.
Ring and test relay drivers with internal clamp diodes are provided.
The complex or real two-wire impedance is set by a scaled, lumped element
Two- to four-wire and four- to two-wire signal conversion is provided by the SLIC in
conjunction with either a conventional or a programmable CODEC/filter.
Longitudinal line voltages are suppressed by a control loop within the SLIC.
Packages are 28-pin, dual-in-line; 32-pin or 44-pin j-leaded chip carrier.
The difference between PBL 3796 and PBL 3796/2 is mainly the longitudinal
CHS VQBAT CHCLK
• On-chip switch mode regulator to
minimize power dissipation
• Programmable, resistive battery feed
with short-loop current limiting
• Line feed characteristics independent
of battery variations
• Tip-ring polarity reversal function
• Tip and ring open circuit state; tip open
with ring active state
- programmable loop current detector
- ring trip detector
• Ring and test relay drivers
• Line terminating impedance, complex
or real, set by a simple external
• Hybrid function with conventional or
• 70 dB longitudinal to metallic balance
• 79 mA peak longitudinal current
• Idle noise < 10 dBrnC, < -80 dBup
Figure 1. Block diagram. Pin numbers refer to the dual-in-line package.